The invention relates to a method and apparatus for dispensing sealant in a countersunk hole prior to fastener installation and more particularly to an applicator tip for dispensing a predetermined amount of sealant in a ring like pattern on the countersink surface.
Many countersunk fasteners on aircraft structures require sealant to be applied to countersunk holes prior to fastener insertion. This is done to keep air and fluids from passing around the fasteners.
U.S. Pat. No. 4,144,625 describes a sealant applicator system where the applicator tip is dipped into a sealant supply then centered, pressed and rotated onto a countersink surface. The rotation of the tip provides a deposit of sealant onto the countersink surface.
U.S. Pat. No. 3,350,774 also describes a sealant applicator for fasteners. An ejector is shown for releasing a predetermined metered quantity of sealant in a uniform manner. The shape and size of the sealant deposit is not controlled.
Presently available sealant tips dispense the sealant into the holes and not onto the countersink thereby not sealing the underside of the countersink head which tends to lead to leaking and corrosion. In addition, the pintails and threads of the fasteners get sealant on them thereby leading to erroneous torque values and clogging of fastener installation tools. Present tips do not meter therefore excessive sealant is used resulting in waste and cleanup time using costly chemicals. Also associated with existing tips is the tendency toward physical fatigue and wrist injuries of the operator due to constant manual twisting of the seal tip in an attempt to cover the entire countersink surface with sealant and actuating the air valve of the air gun coupled to and driving the sealant through the dispensing sealant tip.